1. Field of the Invention
The present invention relates to a torsion beam suspension in which ribs are mounted on both sides of a torsion beam having a U shape of section for connecting a pair of trailing arms in order to form a closed section.
2. Description of the Related Art
A suspension is an apparatus for enhancing a passenger's feeling and a roadholding of a car by connecting a car axis and a car body and thereby preventing a vibration or shock applied to the car axis from a road surface, from being directly transferred to the car body, upon traveling, to avoid a damage of the car body.
Also, because up and down movements of left, right and back directions of wheels are controlled through a torsion of the torsion beam, a roll strength can be also controlled by the torsion beam.
To increase such a torsion strength of the torsion beam, a torsion beam having a U shape of section in which an opening is formed in the rear portion of the car body, has been adopted. Also, to reinforce the torsion beam jointed with the trailing arms, the section shape of the torsion beam has been changed in the both ends of the torsion beam in such a manner that the depth of the opening is deeper toward the jointed parts (shown in FIG. 1).
However, the torsion beam whose section shape has been changed has an efficiency of increasing an warping, rather than an efficiency of increasing the torsion strength in the jointed parts with the trailing arms, thereby concentrating a stress in the jointed parts and allowing it to break the torsion beam.